Currently, reel device is usually applied to reel the wires of corded earphone, mouse, keyboard, charger and the like. The basic principle is that the wire can be reeled along a spiral path or ring path via the elasticity of the spiral spring; when the wire is unreeled, the movement of pulling out the wire is slightly restricted due to the restriction force from the spiral spring, but the restriction force can be easily overcome. Thus, when the user can reel or unreel the wire along a certain path, and the power applied by the user can be slighting restricted, so the user can smoothly reel or unreel the wire.
In recent years, some manufacturers apply reel device to reel or unreel flexible printed circuit board. However, the difference is that they use the device to reel or unreel wider and flat flexible printed circuit board, such as server; one end of a flexible printed circuit board connects to the mainboard of a server, and the other end thereof connects to the hard disk or circuit board of the server is a draw-out structure. When one end of the hard disk or circuit board of the server is pulled out, the reel device unreels the flexible printed circuit board; when one end of the hard disk or circuit board of the server is pushed in, the reel device automatically reels the flexible printed circuit board. Therefore, when the flexible printed circuit board is reeled or unreeled in the limited space of the housing of the server, the reel device can pull out the flexible printed circuit board by a certain length according to the requirement, and the flexible printed circuit board can have a certain tension and balance force, such that the long flexible printed circuit board can keep a safe distance with a lot of high-temperature electronic components in the narrow space.
The conventional flexible printed circuit board reel device is as shown in FIG. 1˜FIG. 2, and its major components include an upper housing 101, a lower housing 102, a rotary sleeve 103, a spiral spring 104 and a sleeve cover 105. The upper housing 101 is provided with 4 upper plastic columns downward and integrally formed with the four corners thereof; the lower housing 102 is provided with 4 upper plastic columns upward and integrally formed with the four corners thereof; the bottom of each of the upper plastic columns 101_1 is provided with a protrusion edge, and the top of each of the lower plastic columns 102_1 is provided with a ring stage corresponding to the protrusion edge. The lower housing 102 is provided with a central shaft 106 upward and integrally formed with the center thereof, and the top of the central shaft 106 is provided with a clamping groove. The rotary sleeve 103 is provided with the axial hole corresponding to the central shaft 106, and the top of the rotary sleeve 103 is provided with an accommodating space 103_1 for accommodating the spiral spring 104, and the outer surface of the rotary sleeve 103 is further provided with a protection sheet 107; a buckle area is formed between the protection sheet 107 and the rotary sleeve 103, and the buckle area is slightly larger than the thickness of one layer of the flexible printed circuit board 108. The assembly process is: first, put the flexible printed circuit board into the buckle area of the rotary sleeve 103; then, put the spiral spring 104 into the accommodating space 103_1 of the rotary sleeve 103, and then the inner center of the spiral spring 104 is caught at the clamping groove of the central shaft 106, and the outer end of the spiral spring 104 is caught at the rotary sleeve 103; afterward, align the axial hole of the rotary sleeve 103 with the central shaft 106 of the lower housing 102, and then insert the rotary sleeve 103 into the central shaft 106; then, insert the protrusion edge at the bottom of the upper plastic column 101_1 of the upper housing 101 into the ring stage at the top of the lower plastic column 102_1 of the lower housing 102 to combine the upper housing 101 and the lower housing 102, such that four upper plastic columns 101_1 and four lower plastic column 102_1 form the two plastic columns at the left side and two plastic columns at the right side; further, one end of the flexible printed circuit board 108 passes through the space between the two plastic columns at the left side, and the other end thereof passes through the space between the two plastic columns at the right side; finally, fasten up the upper housing 101 and the lower housing 102 by screws. The stretching operation principle is: during the initial status, the flexible printed circuit board 108 is reeled around the rotary sleeve 103; when it is necessary to pull out the flexible printed circuit board 108, the user can pull one end or both ends of the flexible printed circuit board 108 to stretch the flexible printed circuit board 108 and make the flexible printed circuit board 108 being the stretching status; at this time, if the user release the flexible printed circuit board 108 or let it freely move with the rotary sleeve 103, the rotary sleeve 103 rotates by the spring force provided by the spiral spring 104, so the flexible printed circuit board 108 can be reeled by the rotary sleeve 103 to return to the initial status in this way, the flexible printed circuit board 108 can be automatically reeled.
The shortcoming of the conventional flexible printed circuit board reel device is: (1) the housing structure composed of the upper housing 101 and the lower housing 102 is only supported by 4 plastic columns; in other words, the housing only has 4 connection points; thus, the upper housing 101 and the lower housing 102 tend to be easily separated by each other, so the structure is not strong and stable enough; (2) the housing only has one spiral spring 104, and the spiral spring 104 is at the top of the rotary sleeve 103; when the flexible printed circuit board 108 is reeled or unreeled, the force and the reaction force generated by the spiral spring 104 becoming tight or loose will concentrate on the upper portion of the rotary sleeve 103, such that the rotary sleeve 103 cannot be balanced, which make the rotary sleeve 103 cannot rotate smoothly or even get damaged.